1. Field of the Invention
The present invention generally relates to a gas insulated bus, and more particularly to a gas insulated bus which is capable of increased conduction capacity.
2. Description of the Prior Art
A gas insulated bus which has an axial cylindrical conductor inside a grounded metal sheath filled with a compressed gas has excellent insulating characteristics. Sulfur hexafluoride (SF6) has generally been used in practice as the insulating gas.
As a way of increasing the current conducting capacity of the conductor in such a gas insulated bus, it has been known to increase the dimension in the radial direction of the sheath and conductor so as to reduce the resistance value of the conductor, while increasing the surface area for radiating heat from the conductor and sheath. Such a known device however, has the defects of increased area of installation and greater cost.
As another method for increasing the current conducting capacity of the conductor, a gas insulated bus which has a circulating device for forced circulation of gas inside the cylindrical conductor or the sheath, as well as a cooling device for cooling the circulated gas, has been known. Such a gas insulated bus, however, has the defects that it is necessary to mount these circulation and cooling devices within the gas insulated bus. Moreover, the bus must be rendered non-conductive when these devices, which are not concerned with rendering the bus conductive, are regularly inspected.